1. Field
Embodiments of the present invention relate to an adaptive cruise control method on an incline to improve traveling performance and stoppage maintenance performance on an incline.
2. Description of the Related Art
Generally, an Adaptive Cruise Control (ACC) system automatically controls longitudinal behavior of a vehicle as a control target based on circumferences of an object ahead of the vehicle using front sensors including a radar, camera, etc. This system may reduce driver stress due to repeated acceleration, deceleration and stoppage required to maintain an appropriate distance with an object ahead of the vehicle during traveling. Automated traveling of the vehicle at a predetermined speed and automated acceleration or deceleration dependent on movement of an object ahead of the vehicle may improve vehicle fuel economy and ensure smooth traffic flow.
The ACC system performs adaptive cruise control by controlling acceleration of the vehicle to follow a target speed preset by a driver. During implementation of adaptive cruise control, deceleration and acceleration of the vehicle are controlled to maintain an appropriate distance with an object ahead of the vehicle using front sensors which function to sense circumferences of the object. This is realized in a manner of giving commands to an acceleration control device, an engine control device and a braking control device based on information from the front sensors of the vehicle, such as a distance between the vehicle and an object ahead of the vehicle, relative speeds, an orientation angle of the vehicle with respect to a movement direction, etc.
However, the ACC system does not consider a gradient of roads and simply controls the vehicle using only acceleration of the vehicle calculated from a wheel speed. Therefore, if the vehicle travels from flat land to an ascent, vehicle speed is reduced below a target speed, causing deterioration in traveling performance. In addition, if brake force suitable for flat land is maintained even on an ascent because a gradient of the ascent is not known, this may cause the vehicle to be pushed rearward due to insufficient brake force. On the contrary, if brake force suitable for flat land is maintained even on a descent, insufficient brake force may cause deterioration in stoppage maintenance performance.